And joseph b



Reissued June 20, 1933 UNITED STATES ARTHUR R. MURPHY, OF PENNS GROVE,

NEW JERSEY, AND JOSEPH B. OESCH, OF

VIENNA, AUSTRIA, ASSIGNORS, BY MESNE ASSIGNMENTS, 'IO E. I. DU PONT DENEMOURS & COMPANY, A CORPORATION OF DELAWARE SULPHONATION OF AROMATIGAMINES No Drawing. Original No. 1,794,861, dated March 3, 1931, SerialNo. 247,254, filed January 16, 1928.

Application fer reissue March 17, 1933. Serial No. 661,352.

it to the amino group.

In general, following the procedures of heretofore known methods ofsulphonating aromatic amines results 1n the formation of mixturesof'products and in many cases in considerable destruction of theoriginal starting material. In fact, the direct sulphonation of aminesin the usual manner does not lead to an ortho sulphonation to an extentsuflicient to make the method practical. Recently there has beendescribed a method whereby these desired products are obtained by theuse of chloro sulphonic acid and a suitable solvent, but this methodpresentscertain disadvantages.

It is therefore an object of our invention to provide a method for thepreparation of the ortho sulphonic acid derivatives of aromatic amineshaving the position para to the amino group occupied by a radical or aportion of a radical other than a hydrogen atom in an economicallypractical manner, and thereby render easily available valuable startingmaterials for use in the preparation of other intermediates anddyestuffs.

Other and further important objects of this invention will becomeapparent from the following description and appended claims.

Our present method makes it possible to obtain ortho sulphonated aminesin good yields, and comprises treating an aromatic amine having theposition para. to the amino group occupied by a radical or a portion ofa radical other than a hydrogen atom with sulfur trioxide. The aminobody is dissolved in a suitable dry organic solvent therefor, such astetrachlorethane, carbon tetrachloride or the like, and subjected totreatment with sulphur trioXide. In order for the solvent to be suitablefor the purpose set forth it must be inert and remain practicallyunattacked by the sulphur trioxide and its boiling point must besufficiently high to permit the completion of the sulphonation byheating. In some cases, it is even possible to use an excess of theamino body as solvent,

but this is not preferred. Ordinarily the reaction appears to proceed intwo steps, accompanied in the first step by the separation of anintermediate compound, presumably the sulphuric acid ester of theoriginal amine or an addition compound. The second step comprises theconversion of the compound first formed into the sulphonic acidderivative. In certain cases, the two steps appear to take placesimultaneously if, in fact, two steps do take place.

The following chemical equation, using as an example meta Xylidine,probably represents the ultimate chemical reaction taking place.

CH1: CH3

A consideration of the reaction given above demonstrates clearly one ofthe advantages of our present process over the heretofore describedmethod using chloro sulphonic acid as the sulphonating agent. The use ofchloro sulphonic acid is accompanied by the evolution of hydrochloricacid, which, on account of its highly corrosive nature, makes itnecessary to employ certain precautionary measures in the design ofapparatus to offset its corrosive effects. The evolution of hydrochloricacid gas also introduces certain complications, due to the fact that thehydrochloric acid evolved entrains some of the solvent, thusnecessitating an additional recovery step which is accompanied withfurther losses of the solvent. It was therefore quite surprising to findthat the ortho sulpho amines could be prepared directly from the parasubstituted amino body by the use of the simple reaction as outlinedabove and with such an easily available sulphonating agent as sulphurtrioxide.

It is to be further noted that on account of the lower molecular weightof sulphur trioxide compared to chloro sulphonic acid and on account ofits lower cost, sulphur triof water by distilling.

oxide possesses a great economical advantage as a sulphonating agent;

Without limiting our invention to any particular procedure the followingenanr ples, in which parts by weight are given, serve to illustrate thepreferred form of our method.

Ewa/mple I One hundred twenty-one (121) parts of meta xylidine(1:3-di-methyl-4-amino-benzene) are added to 500 parts oftetrachlorethane. This mass is agitated and there are introduced belowthe surface 100 parts of sulphur trioXide, produced by distilling S03from oleum. During the introduction of the SO into the mass, thetemperature of the sulphonation mass rises to about 125 C. The mass.which has become fairly thick as the reaction proceeds, is heated toabout 145 C. with refluxing and held at this temperature for about 3hours.

The mass is then poured into 1500 parts of water and neutralized withdilute sodium carbonate solution till the aqueous solution becomesalkaline. The aqueous solution containing the sodium salt of thesulphonic acid is separated from the tetrachlorethane layer andacidified with about 174 parts of 20 B. hydrochloric acid. -To the acidsolution there is now added sulficient salt to give approximately a 10%salt solution, whereupon the product separates and after cooling isfiltered off. The product is 1:3- di-methylAr-amino-f)-sulpho benzene.Some meta Xylidine may be recovered from the tetrachlorethane layer. Thetetrachlorethane may be recovered for reuse by well known methods.

E mamplc ll One hundred forty-three (143) parts of beta naphthylamineare dissolved in 2000 parts of tetrachlorethane and the mass freed It isthen cooled to about 18 C. At this temperature, parts ofsulphur trioxideare added over a period of about one hour. Themass is stirred for about12 hours and is then heated to reflux and stirred at the refluxtemperature for ofl. Somebcta naphthylamine may be re covered from thetetrachlorethane layer.

Other amines such as for example, para toluidine, para chloro aniline,para bromo aniline and the like may be reacted upon in a similar mannerto produce sulphonic acid compounds having the sulphonic acid group inortho position to the amino group.

Throughout the specification and claims the expressions para substitutedamines, aromatic amine having the position para to the amino groupoccupied, an aromatic amine in which the carbon atom para to the carbonatom to which the amino group is attached has no free hydrogen atombound thereto and the like, are used to cover compounds containing aradical, or portion of a radical, other than a hydrogen atom in theposition para to the amino group. e

e are aware of the fact that Various changes may be made in this methodof pro cedure, as for example, that the temperatures, reaction time, andrelative amounts of reagents used may be varied, without departing fromthe spirit of this invention. We therefore do not propose limiting thepatent granted hereon other than as necessitated by the prior art.

\Ve claim as our invention:

1. The process of sulphonating an aro matic amino body in which thecarbon atom para to the carbon atom to which the amino group is attachedhas no free hydrogen atom bound'thereto, substantially in ortho positionto the amino group, which comprises treating the aromatic amino body inwhich the carbon atom para to the carbon atom to which the amino groupis attached has no free hydrogen atom bound thereto in an inert organicsolvent with sulphur trioxide.

2. The process of sulphonating an aromatic amino body in which thecarbon atom para to the carbon atomto which the amino group is attachedhas no free hydrogen atom bound thereto, substantially in ortho positionto the amino group, which comprises treating the aromatic amino body inwhich the carbon atom para to the carbon atom to which the amino groupis attached has no free hydrogen atom bound thereto in tetrachlorethanewith sulphur trioxide.

3. The process of sulphonating an aromatic amino body in which thecarbon atom para to the carbon atom to which the amino group is attachedhas no free hydrogen atom bound thereto, substantially in ortho positionto the amino group, which comprises treating the aromatic amino body inwhichthe carbon atom para to the carbon atom to which the amino group isattached has no free hydrogen atom bound thereto in an inert organicsolvent with sul phur trioxide and heating the solution to effectsulphonation.

4. The process of sulphonating an aromatic amino body in which thecarbon atom para to the carbon atom to which the amino group is attachedhas no free hydrogen atom bound thereto, substantially in ortho positionto the amino group, which comprises treating the aromatic amino body inwhich the free hydrogen atom bound thereto, which comprises treating anamino aromatic compound in which the carbon atom para to the carbon atomto which the amino group is attached has no free hydrogen atom boundthereto in an inert organic solvent therefor,

with sulphur trioxide, heating and refluxing the mass until the reactionis substantially complete and recovering the ortho sulpho aminocompound.

6. The process of preparting an ortho sulpho amino aromatic compound, inwhich the carbon atom para to the carbon atom to which the amino groupis attached has no A free hydrogen atom bound thereto, which L kaline,

comprises treating an amino aromatic compound in which the carbon atompara to the carbon atom towhich the amino group is attached has no freehydrogen atom bound thereto in tetrachlorethane with sulfur trioxide,heating and refluxing the mass until the reaction is substantiallycomplete and recovering the ortho sulpho amino compound.

7. The process of preparing an ortho sulpho amino aromatic compound, inwhich the carbon atom para to the carbon atom to which the amino groupis attached has no free hydrogen atom bound thereto, which comprisestreating an amino aromatic compound in which the carbon atom para to thecarbon atom to which the amino group is attached has no free hydrogenatom bound thereto in tetrachlorethane with sulphur trioxide, heatingthe mass until the reaction is substantially complete, cooling,diluting, rendering a1- separating the aqueous solution formed from thetetrachlorethane, acidifying the aqueous solution and salting out theortho sulpho amino compound from the acidified solution.

8. The process ofpreparingl 3di-methyl- 4-amino-5-sulpho benzene, whichcomprises treating meta xylidine dissolved in tetrachlorethane withsulphur trioxide.

9. The process ofpreparingl 3-dimethyl- 4-amino-5sulpho benzene, whichcomprises treating meta Xylidine dissolved in tetrachlorethane withsulphur trioxide, and heating the mass to approximately boilingtemperatures to effect sulphonation.

10. The {process of preparingl3-d'i-methyl-4-a1nino-5-sulphobenzene,whichcomprises introducing sulphurtrioxide into a mass of meta Xylidine dissolved in an inert dry organicsolvent and heating the mass to effect sulphonation.

11. The process of preparing 1: 3-di-methyll-amino-o-sulpho benzene,which comprises introducing sulphur trioxide into a mass of metaXylidine dissolved in tetrachlorethane and heating the mass underrefluxing conditions to effect sulphonation of the metal Xylidine to 13-di-methyl-4-amino-5-sulpho benzene.

12. The process of preparing 1-sulpho-2- amino-naphthalene, whichcomprises introducing sulphur trioxide into a mass of beta naphthylaminedissolved in an inert dry organic solvent and heating the mass to effectsulphonation.

13. The process of preparing l-sulpho-2- amino-naphthalene, whichcomprises introducing sulphur trioxide into a mass of beta naphthylaminedissolved in tetra-chlorethane and heating the mass under refluxingconditions to eflect sulphonation of the beta naphthylamine to1-sulpho-2-amino-naphthalene.

In testimony whereof, we afiix our signatures.

ARTHUR R. MURPHY.

JOSEPH B. OESCH.

